This invention relates to an improved fluoropolymer-acrylic composition having enhanced weathering properties, particularly to such compositions wherein the fluoropolymer component is made by the polymerization of vinylidene fluoride and, optionally, other perhalogenated monomers and wherein the acrylic component is made by the polymerization of predominantly acrylate and/or methacrylate esters, the improvement residing in the use of (meth)acrylate esters containing 10-50 weight % of straight chain meth(acrylate) esters having at least 3 carbons in the side chain and 50-90 weight % of methyl and/or ethyl (meth)acrylate esters. This composition is useful as a weatherable component of coatings, films and other manufactured articles.
Fluoropolymer-acrylic blends, including those referred to in the art as acrylic-modified fluoropolymers or AMF, are described in the patent literature, but teach that the preferred acrylic component to achieve good weatherability is based on methyl or ethyl (meth)acrylate. Representative of such patent art is U.S. Pat. No. 5,646,201 and EP 960918. These lower alkyl (meth)acrylates are believed to enhance the compatibility of the fluoropolymer and acrylic components, whereas the higher chain esters are believed to result in incompatibility and poor weatherability.
Testing of resistance to UV radiation is used herein as a measure of weatherability of the inventive compositions. Thus, in the examples below, the procedure of ASTM G53-88 was followed to measure the acrylic weight loss for coatings made from the inventive compositions and show that the amount of acrylic degradation is much lower than for a comparative example using (meth)acrylate esters having side chains with only 1-2 carbons.
An improved fluoropolymer-acrylic composition with enhanced weathering properties is provided in which the fluoropolymer component is made by the polymerization of vinylidene fluoride and, optionally, other perhalogenated monomers and in which the acrylic component is made by the polymerization of predominantly acrylate and/or methacrylate esters, the improvement comprising using acrylate and/or methacrylate esters containing 10 to 50 weight % of straight chain (meth)acrylate esters having at least 3 carbons in the side chain and 50 to 90 weight % of straight chain (meth)acrylate esters having 1 or 2 carbons in the side chain.